A conventional rod-type light-emitting element having a light-emitting area increased as compared with light-emitting areas of planar light-emitting elements is disclosed in Patent Literature 1 (JP 2006-332650 A).
In the rod-type light-emitting element, as shown in FIG. 38, a first polarity layer 910 is formed on a substrate 900, and a plurality of rods 920 composed of an active layer that emits light are formed on the first polarity layer 910. The rods 920 are wrapped in a second polarity layer 930. The plurality of rods 920, consisting of the active layer, and the second polarity layer 930 constitute the rod-type light-emitting element.
According to this prior art, the rods 920 each emit light to entire surfaces and therefore attain increase in the light-emitting areas and increase in amount of light emitted from the light-emitting element.
In the prior art, however, the rods 920 are composed of the active layer, and the active layer exclusively serves to increase light emission efficiency by confinement of carriers therein and commonly has high resistance. In the prior art, it is necessary to increase length of the rods in order to increase the light-emitting areas. Thus there has been a problem in that the increase in the length of the rods involves increase in length of the highly resistant active layer, causes decrease in brightness of extremity parts thereof because of failure to pass a sufficient current to the extremity parts, and hinders obtainment of a sufficient emission intensity.
A conventional light-emitting diode of which a section is shown in FIG. 39 has been proposed (see Non-Patent Literature 1). In the light-emitting diode, a core 3001 made of n-type GaN, an InGaN layer 3002, an i-GaN layer 3003, a p-AlGaN layer 3004, and a p-GaN layer 3005 are sequentially formed into shape of a shell so that the latter four cover periphery of the core 3001. The InGaN layer 3002 and the i-GaN layer 3003 constitute an active layer.
In the conventional light-emitting diode, incidentally, selection of material for the core 3001 is restricted because the n-type core 3001 is used as an n-type electrode and because the material is selected with priority given to possession of a function as the n-type electrode. Therefore, it is difficult to freely select the material of the core 3001 and to make the core have desired properties. Thus making the core have the desired properties will increase the manufacturing cost and decrease the production yield.